U.S. regulators warned there may be an increased risk of blood clots connected with birth-control pills made by Bayer AG, and said the issue will be further evaluated in a meeting with advisers in December. Women taking pills containing the hormone drospirenone were 74 percent more likely to experience clots than those on low- estrogen pills, the Food and Drug Administration said in a report released today. An FDA advisory committee will meet Dec. 8 to discuss the findings. Sales of the Yaz family of birth-control pills fell 13 percent in 2010 to 1.11 billion euros ($1.57 billion), making them the company’s second-biggest drug. North American revenue from the pills has fallen as the German drugmaker, based in Leverkusen, faces competition from generics made by Teva Pharmaceutical Industries Ltd.